Mechanism Of Complex Formation Research Articles

A Globally Accurate Neural Network Potential Energy Surface and Quantum Dynamics Studies on Be+(2S) + H2/D2 → BeH+/BeD+ + H/D Reactions.

Chemical reactions between Be+ ions and H2 molecules have significance in the fields of ultracold chemistry and astrophysics, but the corresponding dynamics studies on the ground-state reaction have not been reported because of the lack of a global potential energy surface (PES). Herein, a globally accurate ground-state BeH2+ PES is constructed using the neural network model based on 18,657 ab initio points calculated by the multi-reference configuration interaction method with the aug-cc-PVQZ basis set. On the newly constructed PES, the state-to-state quantum dynamics calculations of the Be+(2S) + H2(v0 = 0; j0 = 0) and Be+(2S) + D2(v0 = 0; j0 = 0) reactions are performed using the time-dependent wave packet method. The calculated results suggest that the two reactions are dominated by the complex-forming mechanism and the direct abstraction process at relatively low and high collision energies, respectively, and the isotope substitution has little effect on the reaction dynamics characteristics. The new PES can be used to further study the reaction dynamics of the BeH2+ system, such as the effects of rovibrational excitations and alignment of reactant molecules, and the present dynamics data could provide an important reference for further experimental studies at a finer level.

Analytical ultracentrifugation study of complex formation between like-charged glycinin and polyelectrolytes: Impact of ionic strength and chain length

In food systems, complexes formed between soybean protein and polyelectrolytes are extensively utilized. However, the mechanisms governing their interactions remain elusive, especially when they possess similar net charges. This study investigates the complexation between like-charged glycinin (11S) and diblock copolymers of polyethylene glycol-block-poly(sodium styrene sulfonate) (PEG-b-PSS) using analytical ultracentrifugation (AUC), a first-principle technique that examines macromolecular characteristics such as molecular weight, stoichiometry, and binding properties. The results reveal that 11S can interact with polyelectrolytes of the same net charges. At ionic strengths above 0.1 M, under a specific concentration of PEG-b-PSS with a PSS degree of polymerization of 33, reducing ionic strength augments the binding strength between PEG-b-PSS and 11S while enhancing the electrostatic repulsion between complexes. Consequently, association occurs as ionic strength decreases from 0.5 to 0.3 M due to the predominance of binding strength, and the association disappears at 0.1 M because electrostatic repulsion becomes predominant. Moreover, PEG-b-PSS with a higher degree of polymerization in the PSS blocks facilitates the formation of insoluble complexes of 11S via soluble intermediates. At an ionic strength of 0.025 M, PEG-b-PSS induces the dissociation of 11S into subunits and peptides. This study demonstrates that by controlling the ionic strength and the degree of polymerization of the polyelectrolyte, it is possible to regulate the binding strength between 11S and polyelectrolyte, as well as the structural changes during binding. Furthermore, this study contributes to understanding the complex formation mechanism between soybean protein and polyelectrolytes, and further expands the application of AUC in studying their binding.

A Neural Network Potential Energy Surface and Quantum Dynamics Study of Ca(1S) + H2(v 0 = 0, j 0 = 0) → CaH + H Reaction.

The reactive collision between Ca and H2 molecules has attracted great interest experimentally due to the key role of the product CaH molecule in the field of astrophysics and cold molecules. However, quantum dynamics calculations for this system have not been reported due to the lack of a global potential energy surface (PES). Herein, a globally accurate PES of the ground-state CaH2 is developed by combining 11365 high-level ab initio points and permutation invariant polynomial neural network method. Based on the newly constructed PES, the state-to-state quantum dynamics calculations for the Ca(1S) + H2 (v 0 = 0, j 0 = 0) → CaH + H reaction are carried out using the time-dependent wave packet method. The dynamic results reveal that the reaction follows the complex-forming mechanism near the reactive threshold, whereas both the indirect insertion mechanism and direct abstraction mechanism have effects at higher collision energies. The newly constructed PES can be used to further study the influence of isotope substitution, rovibrational excitation, and spatial orientation of reactant molecules on reaction dynamics.

Interaction mechanism and compatibility studies of silk protein peptide (SPP) with the common surfactants SDS and DTAB

The molecular interaction of low-molecular-weight SPP with common surfactants (SDS and DTAB) is a more complicated process than has been long believed. In this work, the interaction mechanism between SDS/DTAB and SPP was proposed using multiple methods including conductivity measurements, ST, UV-vis, FT-IR, DLS, fluorescence spectroscopy, and molecular docking simulations. Moreover, the foaming properties of the mixed systems were studied, and they were evaluated as cosmetics preservatives. The effects of various surfactant and protein concentrations and ratios on compatibility and functionality were studied. Based on the results, the mechanism of complex formation was identified as a cooperative van der Waals interaction followed by hydrophobic interaction and hydrogen bonding. A simpler head group leads to easier aggregation and interaction with the SPP, the formation of smaller-sized complexes, and a weaker impact on the fluorescence intensity. Thus, SDS monomers easily aggregate on SPP chains, leading to a stronger influence on the final secondary structure of SPP. This was confirmed by multiple spectroscopy methods. Comparing its single surfactant system, the SDS-SPP solution demonstrates better foaming power and the DTAB-SPP solution shows higher bacteriostatic activity. The good compatibility between SDS/DTAB and SPP can improve the functional properties of SDS or DTAB as well as lower the optimal concentration of each component. These results provide data and theoretical support for the design of cosmetic product formulas.

Quantum study of the competition and interplay between complexes resulting from the interaction of methylamine and halogen cyanides

In this study, quantum calculations were conducted to investigate the nature, formation mechanism, and properties of complexes resulting from the interaction between methylamine (MA) and halogen cyanide molecules (XCN, X = F, Cl, Br, and I). Three types of complexes were formed from the interaction of MA with XCN, characterized as Tetrel bond-hydrogen bond (TB-HB), Tetrel bond (TB), and Halogen bond (XB), denoted by symbols A, B, and C, respectively. The data obtained from the interaction energy indicated that complexes with structure C are significantly more stable compared to the other two structures. Molecular electrostatic potential map (MEP) analysis revealed that the size of the σ-hole of the halogen atom ligand plays a crucial role in the stability of structure C complexes. To further evaluate the properties of the resulting complexes, various analyses were conducted, including Molecular electrostatic potential map (MEP), Geometry optimization, Spectroscopy, Interaction energy (SE), Natural bond orbital (NBO), Atoms in molecules (AIM), Non-covalent interaction index (NCI), and Energy decomposition analysis (EDA).

Deep learning prediction of rainfall-driven debris flows considering the similar critical thresholds within comparable background conditions

Machine learning has been widely applied to predict the spatial or temporal likelihood of debris flows by leveraging its powerful capability to fit nonlinear features and uncover underlying patterns or rules in the complex formation mechanisms of debris flows. However, traditional approaches, including some current machine learning-based prediction models, still have limitations when used for debris flow prediction. These include the lack of a specific network structure or model to consider the updating of debris flow critical conditions in relation to geographical background conditions, limiting the universality of prediction models when transferring them to different places. In this study, this article proposes a deep learning network designed to predict the spatiotemporal probability of rainfall-induced debris flows, incorporating the Similarity Mechanism of Debris Flow Critical Conditions (SM-DFCC). The model comprehensively integrates the mining of rainfall-triggering features and couples them with geographical background features to fit the nonlinear relationship with debris flow formation. The model underwent training using data on various historical debris flows triggered by different storms across Liangshan Prefecture from 2020 to 2022. The results indicated that: (i) the method is effective in predicting the spatiotemporal likelihood of debris flows under catchment units, with accuracy scores (ACC) ranging from 0.724 to 0.835; (ii) after optimization using the AVOA algorithm, the predictive performance of the model significantly improved, with an increase of 27.24% in ACC scores for SVC and 8.81% for XGBoost; and (iii) factor importance analysis revealed that rainfall triggering factors have higher cumulative contribution rates when distinguishing between the occurrence and non-occurrence of debris flows. In addition, taking a rainfall storm on 06, September 2020 as a case, this research quantitatively revealed the pattern of debris flow formation, where high-frequency disaster areas exhibit lower rainfall thresholds of debris flows, represented by absolute energy (AE). Despite these findings, the accuracy and reliability of rainfall data still remain the most challenging obstacle in basin/regional-scale debris flow prediction when applying this method. The integration of multiple sources of rainfall data, including station data, satellite rainfall, radar rainfall, etc., is necessary to accurately quantify the impact of rainfall on debris flow formation when applying this method to debris flow monitoring and early warning tasks. Overall, this method shows great potential in providing a scientific reference for the construction of debris flow monitoring and early warning systems in the future.

Investigation of the effect of ultrasonication on starch-fatty acid complexes and the stabilization mechanism

The complexation of physically modified starch with fatty acids is favorable for the production of resistant starch. However, there is a lack of information on the effect of ultrasonication (UC) on the structure and properties of starch complexes and the molecular mechanism of the stabilization. Here, the multi-scale structure and in vitro digestive properties of starch-fatty acid complexes before and after UC were investigated, and the stabilization mechanisms of starch and fatty acids were explored. The results showed that the physicochemical properties and multi-scale structure of the starch-fatty acid complexes significantly changed with the type of fatty acids. The solubility and swelling power of the starch-fatty acid complexes were significantly decreased after UC (P < 0.05), which facilitated the binding of starch with fatty acids. The XRD results revealed that after the addition of fatty acids, the starch-fatty acid complexes showed typical V-shaped complexes. In addition, the starch-fatty acid complexes showed a significant increase in complexing index, improved short-range ordering and enhanced thermal stability. However, the differences in the structure and properties of the fatty acids themselves resulted in no significant improvement in the multi-scale structure of maize starch-palmitic acid by UC. In terms of digestibility, especially the complexes after UC were more compact in structure, which increased the difficulty of enzymatic digestion and thus slowed down the digestion process. DFT calculations and combined with FT-IR analysis showed that non-covalent interactions such as hydrogen bonding and hydrophobic interactions were the main driving force for the formation of the complexes, with binding energies (lauric acid, myristic acid and palmitic acid) of −30.50, –22.14 and −14.10 kcal/mol, respectively. Molecular dynamics simulations further confirmed the molecular mechanism of inclusion complex formation and stabilization. This study is important for the regulation of starchy foods by controlling processing conditions, and provides important information on the role of fatty acids in the regulation of starch complexes and the binding mechanism.

Harnessing the Power of a Novel Triple Chelate Complex in Fermented Probiotic Dairy Products: A Promising Solution for Combating Iron Deficiency Anemia.

This study discovered and examined novel triple chelate complexes involving iron, ascorbic acid, and essential amino acids (AsA-Fe-AmA triple chelate complexes) for the first time. The mechanism of complex formation was studied using FTIR spectroscopy and quantum chemical modeling. The produced complexes were shown to be suitable for fortifying food items with a pH of 3-7 that have not been exposed to heat treatment at temperatures over 75 °C for more than 15 min. Thus, it can be said that the concentration for milk fortification should be 0.005 mol/L or less. In vivo experiments in rats models revealed that the synthesized complexes increased serum iron levels after a single application to reference values within 24 h of oral administration. The iron level increased by 14.0 mmol/L at 2 mL dose of the complex. This fact makes it possible to consider the use of developed complexes and developed fermented dairy products for the prevention of iron deficiency and iron deficiency anemia. Research on the effect of discovered compounds on the physicochemical and organoleptic qualities of milk was conducted. Furthermore, iron ascorbate threoninate, iron ascorbate methioninate, iron ascorbate lysinate, and iron ascorbate tryptophanate all had a beneficial effect on Lacticaseibacillus rhamnosus at concentrations as low as 0.0005 mol/L, which is significant for milk fermentation. A study of fermented milk products revealed that the most effective AsA-Fe-AmA triple chelate complex is iron ascorbate lysinate, which might be further investigated as a viable molecule for dietary fortification in iron deficiency anemia. It was found that fortified fermented milk products had a titratable acidity of 67 ± 1°T, pH of 4.38 ± 0.05, and a viscosity of 2018 ± 142 Pa·s.

Quercetin, a natural flavonoid, protects against hepatic ischemia–reperfusion injury via inhibiting Caspase-8/ASC dependent macrophage pyroptosis

IntroductionHepatic ischemia–reperfusion injury (IRI) is an inevitable adverse event following liver surgery, leading to liver damage and potential organ failure. Despite advancements, effective interventions for hepatic IRI remain elusive, posing a significant clinical challenge. The innate immune response significantly contributes to the pathogenesis of hepatic IRI by promoting an inflammatory cytotoxic cycle. We have reported that blocking GSDMD-induced pyroptosis in innate immunity cells protected hepatic IRI from inflammatory injury. However, the search for effective pyroptosis inhibitors continues. ObjectivesThis study aims to evaluate whether quercetin, a natural flavonoid, can inhibit GSDMD-induced pyroptosis and mitigate hepatic IRI. MethodsWe established the hepatic IRI murine model and cellular pyroptosis model to evaluate the efficacy of quercetin. ResultsQuercetin effectively alleviated hepatic IRI-induced tissue necrosis and inflammation. We found that during hepatic IRI, the cleavage of GSDMD occurred in hepatic macrophages, but not in other non-parenchymal cells. Quercetin inhibited the cleavage of GSDMD in macrophages. Moreover, we found that quercetin blocked the ASC assembly to inhibit the formation of NLRP3 inflammasomes and AIM2 inflammasomes, suppressing macrophage pyroptosis. Co-immunoprecipitation experiments confirmed that quercetin inhibited the interaction between ASC and Caspase-8, which is the mechanism of ASC complex and inflammasome formation. Overexpression of Caspase-8 abolished the anti-pyroptosis effect of quercetin in NLRP3 and AIM2 inflammasome signaling. Furthermore, we found that the hepatoprotective activity of quercetin was reduced in myelocytic GSDMD-deficient mice. ConclusionOur findings suggest that quercetin has beneficial effects on hepatic IRI. Quercetin could attenuate hepatic IRI and target inhibition of macrophage pyroptosis via blocking Caspase-8/ASC interaction. We recommend that quercetin might serve as a targeted approach for the prevention and personalized treatment of hepatic IRI in perioperative patients.

Investigation of the formation mechanism of the pepper starch-piperine complex

In this study, a new carrier for loading piperine was prepared using pepper starch, and its interaction mechanism was investigated. The porous pepper starch-piperine complex (PPS-PIP) showed higher loading efficiency (76.15 %) compared to the porous corn starch-piperine complex (PCS-PIP (52.34 %)). This may be ascribed to the hemispherical shell structure of porous pepper starch (PPS) compared to the porous structure of porous corn starch (PCS) based on the SEM result. PPS-PIP had smaller particle size (10.53 μm), higher relative crystallinity (38.95 %), and better thermal stability (87.45 °C) than PCS-PIP (17.37 μm, 32.17 %, 74.35 °C). Fourier transform infrared spectroscopy (FTIR) results implied that piperine not only forms a complex with amylose but may also be physically present in porous starch. This was demonstrated by the short-range order and X-ray type. Molecular dynamics simulations confirmed that hydrogen bonding is the primary interaction between amylose and piperine. Besides the formation of the amylose-piperine complex, some of the piperine is also present in physical form.

Comparison of Non-Covalent and Covalent Interactions between Lactoferrin and Chlorogenic Acid.

Adding polyphenols to improve the absorption of functional proteins has become a hot topic. Chlorogenic acid is a natural plant polyphenol with anti-inflammatory, antioxidant, and anticancer properties. Bovine lactoferrin is known for its immunomodulatory, anticancer, antibacterial, and iron-chelating properties. Therefore, the non-covalent binding of chlorogenic acid (CA) and bovine lactoferrin (BLF) with different concentrations under neutral conditions was studied. CA was grafted onto lactoferrin molecules by laccase catalysis, free radical grafting, and alkali treatment. The formation mechanism of non-covalent and covalent complexes of CA-BLF was analyzed by experimental test and theoretical prediction. Compared with the control BLF, the secondary structure of BLF in the non-covalent complex was rearranged and unfolded to provide more active sites, the tertiary structure of the covalent conjugate was changed, and the amino group of the protein participated in the covalent reaction. After adding CA, the covalent conjugates have better functional activity. These lactoferrin-polyphenol couplings can carry various bioactive compounds to create milk-based delivery systems for encapsulation.

Formation mechanism of quinoa protein hydrolysate-EGCG complexes at different pH conditions and its effect on the protein hydrolysate-lipid co-oxidation in emulsions

This study aimed to investigate the interaction, structure, antioxidant, and emulsification properties of quinoa protein hydrolysate (QPH) complexes formed with (−)-epigallocatechin gallate (EGCG) at pH 3.0 and 7.0. Additionally, the effect of pH conditions and EGCG complexation on protein hydrolysate-lipid co-oxidation in QPH emulsions was explored. The results indicated that QPH primarily interacted with EGCG through hydrophobic interactions and hydrogen bonds. This interaction led to alterations in the secondary structure of QPH, as well as a decrease in surface hydrophobicity and free SH content. Notably, the binding affinity between QPH and EGCG was observed to be higher at pH 7.0 compared to pH 3.0. Consequently, QPH-EGCG complexes exhibited more significant enhancement in antioxidant and emulsification properties at pH 7.0 than pH 3.0. The pH level also influenced the droplet size, ζ-potential, and interfacial composition of emulsions formed by QPH and QPH-EGCG complexes. Compared to QPH stabilized emulsions, QPH-EGCG stabilized emulsions were more capable of mitigating destabilization during storage and displayed fewer lipid oxidation products, carbonyl generation, and sulfhydryl groups and fluorescence loss, which implied better oxidative stability of the emulsions. Furthermore, the QPH-EGCG complexes formed at pH 7.0 exhibited better inhibition of protein hydrolysate-lipid co-oxidation. Overall, these findings provide valuable insights into the potential application of QPH and its complexes with EGCG in food processing systems.

Preliminary analyses of radiophotoluminescence centers in a recently developed Ag-doped alkali-phosphate glass (SAPANS)

The mechanism behind radiophotoluminescence (RPL) emission in Ag-doped alkali-phosphate glass remains unclear. To contribute to resolving this issue, the authors measured and analyzed the temporal change of electron spin/paramagnetic resonance (ESR) spectrum of a recently developed, weather-resistant RPL glass, named “SAPANS,” after irradiation with X-rays. As a result, a continuous gradual increase in Ag2+-derived signals was observed even at four weeks post-irradiation, which corresponded well with the time build-up pattern of the RPL of SAPANS. In contrast, the signals derived from phosphorous-oxygen-hole centers (POHC) rapidly decreased over a few days. The peaks of Ag0 and Ag2+ were not successfully separated from the ESR spectra because of the possible overlap of unidentified peaks, which implies a complex mechanism of RPL-center formation in Ag-doped alkali-phosphate glass that requires further investigation.

Unprecedented Pyrazine‐Bridged Guanidinate Rare Earth Complexes Through a Bridge Splitting Reaction Path

AbstractThe development of reaction pathways and ancillary ligand scaffolds is essential in the pursuit of higher nuclearity rare earth metal clusters that are relevant in storage materials and catalysis. Guanidinate anions represent attractive ligands due to their high degree of customizability allowing for facile alterations of both their steric and electronic properties. Here, we demonstrate an unprecedented bridge splitting reaction that shifts chloride anions in favor of a bridging neutral pyrazine to give pyrazine‐bridged dinuclear guanidinate rare earth complexes, [{(Me3Si)2NC(NiPr)2}2RECl]2(μ‐pyz) (RE =Y (1) and Er (2), pyz=pyrazine). Each six‐coordinate metal center is ligated by two guanidinates, one chloride ligand, and one nitrogen atom from the bridging pyrazine unit. The molecules were characterized by X‐ray crystallography, IR, NMR, and UV‐Vis spectroscopy. DFT calculations conducted on 1 provide insight into both the bonding picture and the mechanism of complex formation. This type of reaction constitutes a seminal application of a bridge splitting mechanism to the rare earth metals.

A globally accurate neural network potential energy surface and quantum dynamics study of Mg+(2S) + H2 → MgH+ + H reaction

A globally accurate ground-state MgH2+ potential energy surface (PES) is constructed by neural network method based on 12,056 high-level ab initio points. On the PES, the dynamics calculations of the Mg+(2S) + H2/HD (v0 = 0, j0 = 0) reaction are performed using the time-dependent wave packet method. The branching ratio (MgD+/MgH+) in the Mg+ + HD reaction is much larger than one in most studied collision energies. The dynamics results imply that the title reaction follows the complex-forming mechanism near the threshold, and the direct abstraction process gradually plays the dominant role as the collision energy increases.

Insights into formation and stability mechanism of V7-type short amylose-resveratrol complex using molecular dynamics simulation and molecular docking

Pre-formed V-type amylose as a kind of wall material has been reported to carry polyphenols, while the interaction mechanism between V-type amylose and polyphenol is still elusive. In this work, the formation and stability mechanism of a V7-type short amylose-resveratrol complex was investigated via isothermal titration calorimetry, molecular dynamics, and molecular docking. The results presented that two stoichiometric ratios of resveratrol to short amylose were calculated to 0.120 and 0.800, and the corresponding main driving force was hydrogen bonding and hydrophobic interaction, respectively. The folding and unfolding conformation of V7-type short amylose chains appeared alternately during the simulation. Resveratrol tended to be bound in the short amylose helix between 40 ns and 80 ns to form a more stable complex. Hydrogen bonds between resveratrol molecule and O6 at the 22nd glucose molecule/O2 at the 24th glucose molecules and hydrophobic interaction between resveratrol molecule and glucose molecules (19th, 20th, 21st and 23rd) could be found.

Comparison of acidity and chemical composition of summertime cloud water and aerosol at an alpine site in Northwest China: Implications for the neutral property of clouds in the free troposphere

Aerosol and cloud acidity are essential to human health, ecosystem health and productivity, as well as climate effects. The main chemical composition of cloud water greatly varies in different regions, resulting in substantial differences in the pH of cloud water. However, the influences of the anthropogenic emissions of acidic gases and substances, alkaline dust components, and dicarboxylic acids (diacids) on the ground concerning the acidity of cloud water in the free troposphere of the Guanzhong Plain, China, remain clear. In this study, cloud water and PM2.5 samples were simultaneously collected in the troposphere (Mt. Hua, 2060 m a.s.l). The results indicated that the cloud water was alkaline (pH = 7.6) and PM2.5 was acidic (pH = 3.2). These results showed the neutral property of clouds collected in the heavily polluted Guanzhong Plain, although most previous studies always considered acidity as a marker of pollution. The sulfate (SO42−), nitrate (NO3−), and ammonium (NH4+) (SNA) of particulate matter and cloud water in the same period were compared. SO42− was dominant in particulate matters (accounting for 63.4 % of the total SNA) but substantially decreased in cloud water (only 30.1 % of the total SNA), whereas NO3− and NH4+ increased from 28.5 % and 8.2 % to 39.8 % and 30.2 %, respectively. This could be attributed to the complex formation mechanism and sources of SO42− and NO3− in the cloud. The results of ion balance indicated that a significant deficit of inorganic anion equivalents was observed in the cloud water samples. The high concentration of diacids in the cloud phase (1237.4 μg L−1) may facilitate the formation of salt complexes with NH4+, thus influencing the acidity of the cloud water. The pH of cloud water has increased in recent decades due to the sustained reduction of sulfur dioxide, which may also affect the acidity of future precipitation.

State-to-State Quantum Dynamics Study of Intramolecular Isotope Effects on Be(1S) + HD (v0 = 2, j0 = 0) → BeH/BeD + H/D Reaction.

The dynamic mechanisms and intramolecular isotope effects of the Be(1S) + HD (v0 = 2, j0 = 0) → BeH/BeD + H/D reaction are studied at the state-to-state level using the time-dependent wave packet method on a high-quality potential energy surface. This reaction can proceed along the indirect pathway that features a barrier and a deep well or the smooth direct pathway. The reaction probabilities, total and state-resolved integral cross sections, and differential cross sections are analyzed in detail. The calculated dynamics results show that both of the products are mainly formed by the dissociation of a collinear HBeD intermediate when the collision energy is slightly larger than the threshold. As the collision energy increases, the BeH + D channel is dominated by the direct abstraction process, whereas the BeD + H channel mainly follows the complex-forming mechanism.

Structural insights into thermophilic chaperonin complexes

Group I chaperonins are dual heptamer protein complexes that play significant roles in protein homeostasis. The structure and function of the Escherichia coli chaperonin are well characterized. However, the dynamic properties of chaperonins, such as large ATPase-dependent conformational changes by binding of lid-like co-chaperonin GroES, have made structural analyses challenging, and our understanding of these changes during the turnover of chaperonin complex formation is limited. In this study, we used single-particle cryogenic electron microscopy to investigate the structures of GroES-bound chaperonin complexes from the thermophilic hydrogen-oxidizing bacteria Hydrogenophilus thermoluteolus and Hydrogenobacter thermophilus in the presence of ATP and AMP-PNP. We captured the structure of an intermediate state chaperonin complex, designated as an asymmetric football-shaped complex, and performed analyses to decipher the dynamic structural variations. Our structural analyses of inter- and intra-subunit communications revealed a unique mechanism of complex formation through the binding of a second GroES to a bullet-shaped complex.

Theoretical study of the O(3P) + CN(X2Σ+) → CO(X1Σ+) + N(2D)/N(4S) reactions.

The barrierless exothermic reactions between atomic oxygen and the cyano radical, O(3P) + CN(X2Σ+) → CO(X1Σ+) + N(2D)/N(4S), play a significant role in combustion, astrochemistry, and hypersonic environments. In this work, their dynamics and kinetics are investigated using both wave packet (WP) and quasi-classical trajectory (QCT) methods on recently developed potential energy surfaces of the 12A', 12A,″ and 14A″ states. The product state distributions in the doublet pathway obtained with the WP method for a few partial waves show extensive internal excitation in the CO product. This observation, combined with highly oscillatory reaction probabilities, signals a complex-forming mechanism. The statistical nature of the reaction is confirmed by comparing the WP results with those from phase space theory. The calculated rate coefficients using the WP (with a J-shifting approximation) and QCT methods exhibit agreement with each other near room temperature, 1.77 × 10-10 and 1.31 × 10-10cm3molecule-1s-1, but both are higher than the existing experimental results. The contribution of the quartet pathway is small at room temperature due to a small entrance channel bottleneck. The QCT rate coefficients are further compared with experimental results above 3000K, and the agreement is excellent.